The Walking Dead star Norman Reedus has elaborated on the “dark, dark secret” shared between his Daryl Dixon and Michonne (Danai Gurira), who earlier in Season Nine were revealed to share matching ‘X’ scars.

“I think when Rick was on a run, they had a little S&M fun,” Reedus joked on live aftershow Talking Dead.

More seriously, Reedus teased, “It is a backstory actually, but you’ll find out what happened with that is something that just happened between Michonne and Daryl.”

“And the rest of the group don’t really know what that is yet, but something horrific happened right there and you’ll learn later, with the new people coming into the group, that there’s certain lines that you don’t cross but we crossed them,” Reedus explained.

“And just between she and I, that’s our little secret, but it’s a really dark, dark secret.”

Former co-star Michael Cudlitz, who returned to The Walking Dead this past half season as director, previously teased revelations will come and that the explanation belongs to a “really f—ed up story.”

“Some of the stuff we know why it changed, and some of the stuff we’re going to discover. We will discover where those Xs come from. It’s a really f—ed up story,” Cudlitz said in November.

“It’s a big, really f—ed up thing that happened during that break. At some point, we will find out about it. You will find out eventually what that is. It was bad.”

Daryl and Michonne addressed their shared trauma in Sunday’s mid-season premiere when returning to Hilltop with a slain Jesus (Tom Payne), reconnecting over their inability to recover the body of the believed dead Rick Grimes (Andrew Lincoln) six years earlier.

“Thank you for trying to find him. And... for after,” Michonne told Daryl, who previously admitted to Carol (Melissa McBride) he spent much of a six-year time jump searching for Rick’s remains following his apparent death in a bridge explosion.

“We’ll definitely be telling the story of what happened there, and what’s kind of exciting about a six-year jump is that there is the opportunity to go back and tell some of those stories. So we’ll see some of what has happened,” showrunner Angela Kang previously told EW.

“But it’s a deep, emotional story for Michonne, and for Daryl too. So I’m excited for people to experience that. It’s something that certainly has had an effect on Michonne in a deep and particular way. So that’s something that we wanna tell people what that’s about at some point.”